Project number: 1999-225
Project Status:
Completed
Budget expenditure: $46,251.00
Principal Investigator: Alexander Murray
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 28 Jun 1999 - 16 May 2001
Contact:
FRDC
SPECIES

Need

The mass mortality events are very economically and ecologically damaging. Economic damage occurs acutely in the short-term due to the need to close the fishery during events and damage also occurs in the longer term owing to the removal of large numbers of fish during the event.

No model exists of the spatial propogation of a viral epidemic in an exploited fish population, we will derive such a model. This model will be aimed less at predicting the spread of a particular mass mortality event and more at the understanding of the dynamics of the event. Using the model we will be able to assess hypothesises concerning the factors which control the mass mortality and hence focus future study on the most sensitive processes. The model will also show the conditions under which these events may recur. We will also be able to assess the potential for management intervation to halt an ongoing epidemic or prevent further outbreaks. The model will also integrate all the aspects of the spread of the mass mortality events, showing linkages within the existing data and showing those areas for which adaquate data is lacking.

It should also be noted that damaging epidemics among wild caught and farmed marine fisheries are not infrequent and that modified versions of the model may have future applications to other fisheries.

Objectives

1. We will construct a 1-D SIR (Susceptible, Infected, Removed) model of the spread of the pilchard mass mortality events of 1995 and 1998/9
2. We will analyse the effect of different modes of local transmission on the mass mortality's dynamics.
3. We will produce a literature review of similar mass mortalities and the modelling approaches used to analyse them.
4. We will refine the SIR model to include different transmission process functions and data obtained by other pilchard mortality study projects, in particular the Fisheries WA lead study on viral transmission.
5. We will review the observations, including those obtained in concurrent studies, to provide the tightest possible constraints on the ranges of model parameters.
6. We will analyse the effects of fisheries management strategies on pathogen transmission, in particular we will test the viability of a 'fire break' policy.
7. We will construct a simple model of the recovery of the fishery to investigate the period required for the stocks to become vulnerable to renewed mortality.
8. We will develop a Graphical User Interface (GUI) to display the local and geographical spread of pathogens.
9. We will produce an initial report detailing the approaches used both by us and other modellers of epidemics.
10. We will produce a final report detailing the final form of the model produced and incorporating analysis of model structure, parameters and results.
11. We will present this work at a nationally significant scientific meeting in 2000.

Final report

ISBN: 0-643-06233-5
Author: Alexander Murray

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